JP5604684B2 - Steam turbine and method for cooling the steam turbine - Google Patents

Description

  The invention relates to a steam turbine as described in claim 1 and a suitable method for cooling the steam turbine according to claim 6.

  A steam turbine is driven as a working medium by live steam, which can have a temperature of several hundred degrees. For this purpose, the live steam flows into a flow path formed between the rotor and the stator, and as a result, this live steam protrudes into this flow path, the stator guide blade and the rotor rotor blade. Washed around. Thereby, the live steam is expanded and cooled to a lower pressure. The thermal energy released at that time is converted into rotational energy of the rotor, and the rotational energy is used to drive a generator or work machine connected to the rotor.

  In order to realize the high performance of the steam turbine, a high working temperature of the live steam and accordingly a large heat burden on each component of the steam turbine are required accordingly. However, these components, particularly those that are subjected to heat loads, must be sufficiently cooled in order to ensure safe driving of the steam turbine.

  In this connection, Patent Document 1 discloses an apparatus in which cooling steam is supplied from the outside to the steam turbine in addition to live steam. Cooling steam, in particular heat load, via corresponding conduits to the outer housing of the turbine stator, the outer housing cooling holes, the flow space between the outer housing and the inner housing of the stator, and the inner housing cooling holes. In the region of the steam turbine where the air acts, the device is fed into the thrust balance piston of the rotor, and the thrust balance piston is intentionally cooled. An additional sealing element separates this cooling steam chamber from the adjacent live steam chamber. In that case, on the other hand, the sealing element should be sealed as much as possible to prevent the cooling steam from flowing back into the live steam chamber, even in the case of a change in the state of steam that may occur during load changes. Need to be. On the other hand, however, the sealing element also needs to be in an unsealed state in order to reduce the pressure load fast enough and reliably in case of an emergency shutdown of the turbine power supply. Therefore, the sealing element must be designed to meet two conflicting requirements.

  Further, Patent Document 1 discloses an embodiment in which an external lateral conduit is additionally provided between a live steam conduit and a cooling steam conduit outside the steam turbine. This lateral conduit is an excessive difference between the area to be cooled and the inflow area of the flow path by introducing cooling steam in addition to the live steam when the pressure drops suddenly in the live steam conduit. Used to avoid loads due to pressure.

European Patent Application No. 2067933

  The object of the present invention is to provide an improved steam turbine and an improved method for cooling such a steam turbine.

  This problem is solved by a steam turbine having the features of claim 1 and a suitable method having the features of claim 6.

  The present invention provides a portion of the live steam from the flow path directly to the cooling steam by an additional pressure balance lateral connection disposed between the flow path and the cooling steam supply pipe. It is configured. As a result, it is possible to thermodynamically connect the live steam chamber and the cooling steam chamber of the turbine via this lateral connection portion, and thus always achieve a pressure balance. There is no need to make such a high demand for additional sealing elements that define areas where large heat loads are applied, such as areas with live steam, such as thrust balance pistons of rotors that engage the stator. This is because the pressure difference between the two spaces is small.

  When the end of the pressure balance lateral connection joins the flow path radially outwards, the radial balance is applied to balance the pressure downstream of the blades while the turbine is driving steadily. Directional pressure balance can be utilized. In other words, there is a pressure difference that has a higher static pressure on the outside in the radial direction of the flow path in the flow in which the swirl that is physically created in the flow path acts. As a result, a pressure higher than the pressure acting on the rotor acts on the inner housing of the stator downstream of the guide blade. Such high pressure in contact with the pressure balance lateral connection also directly defines the high pressure in the cooling steam chamber via the pressure balance lateral connection. Thereby, even if the load changes during steady driving, the flow direction is not locally reversed. In addition, in the event of an emergency shutdown of the turbine power supply, a space connection between the live steam and the cooling steam, along with a pressure balance lateral connection, through which excess cooling steam can be emptied directly There are parts, so that the sealing element is less loaded.

  Preferably, the pressure balance lateral connection is provided in the inner housing of the stator and in the present invention especially in the vicinity of the inflow region of the flow path, so that the local maximum pressure of the flow path is branched as a result. be able to. Furthermore, when the pressure balance lateral connection portion joins the cooling steam conduit in the vicinity of a region where a large heat load acts, the passage of the pressure balance lateral connection portion can be shortened.

It is sectional drawing of the steam turbine 1 in this invention which has a stator and rotor which comprise an internal housing and an external housing.

  The present invention will be exemplarily described based on the drawings. FIG. 1 is a cross-sectional view of a steam turbine 1 having a stator 2 and a rotor 3 each having an inner housing 21 and an outer housing 22. A flow path 4 is formed between the stator 2 and the rotor 3, and a rotor blade row 33 of the rotor 3 and a guide blade row 23 of the stator 2 are alternately provided in the axial direction in the flow path 4. ing. Live steam is supplied to the inflow region 41 of the flow path 4 through the live steam conduit 5. The live steam thus flowed in then flows around the rotor blade row 33 and the guide blade row 23 toward the downstream in the flow path 4 and is expanded and cooled. The rotor 3 is rotated by the heat energy released thereby. When the rotor 3 rotates in the stator 2 to which the rotor 3 is fixed, there may be a region 34 where a large heat load acts locally. In this case, the region 34 needs to be cooled. Such a region is, for example, a thrust balance piston 35 formed in the rotor while operating in a corresponding recess of the stator 2 as the rotor 3 rotates.

  An additional cooling steam conduit 6 is provided for cooling the region 34 where such a large heat load is applied. In the present embodiment, the cooling steam conduit 6 has a flow space formed between an external conduit 61 that circulates to the external housing 22 from the outside, an external housing cooling hole 62, and the external housing 22 and the internal housing 21. 63 and at least one internal housing cooling hole 64. The internal cooling hole 64 is provided in the internal housing 21 and fluidly connects the flow space 63 and the gap space provided between the thrust balance piston 35 and the internal housing 21. As shown, both the cooling steam conduit and the live steam conduit may include additional valves for controlling the amount of each steam. Furthermore, in order to isolate the two steam chambers in the turbine 1, additional sealing elements (not shown in detail in FIG. 1) are arranged where the live steam chamber and the cooling steam chamber are in close contact. It is installed. However, since there is a pressure difference between the cooling steam and the live steam, particularly high demands should be placed on these sealing elements. On the other hand, the sealing element needs to be designed to be “permeable” in order to rapidly reduce excess cooling steam in the event of an emergency shutdown of the power supply.

  In the present invention, a pressure balance lateral connection 7 is provided between the flow path 4 and the cooling steam conduit 6 in order to reduce the requirement for such a sealing element as much as possible. In the illustrated embodiment, the lateral connection portion 7 is disposed in the vicinity of the inflow region 41 of the live steam toward the flow path 4 and in the vicinity of the region 34 where a large heat load acts. For example, a part of the live steam can be directly supplied to the cooling steam from the flow path 4 via the pressure balance lateral connection portion 7 formed as a hole in the inner housing 21 of the stator 2. The lateral connection 7 provides a pressure balance between the live steam chamber and the cooling steam chamber. At the same time, the lateral connection portion 7 can be used as a “bypass” for discharging the excess cooling medium from the cooling steam chamber to the live steam chamber when the power supply is urgently cut off. Since the requirements for the sealing element can be reduced overall, the material costs can be greatly reduced as a result.

  The present invention is not limited to the embodiment described above. Rather, combinations, changes, and complements of features that can be further embodiments based on the inventive idea can be conceived. The pressure balance lateral connection 7 may be directly circulated in a region where the cooling steam passes and a large heat load acts. In this case, a part of the live steam from the flow path is supplied to the cooling steam for the first time in the region. As shown in the figure, the pressure balance lateral connection portion 7 may be composed of a region oriented in the radial direction and a region oriented in the axial direction. It may be formed obliquely through the inner housing from the inner housing to the inner housing cooling hole.

DESCRIPTION OF SYMBOLS 1 Steam turbine 2 Stator 3 Rotor 4 Flow path 5 Live steam conduit 6 Cooling steam conduit 7 Pressure balance lateral connection part 21 Internal housing 22 External housing 23 Guide blade row 33 Rotor blade row 34 Area where large heat load acts 35 Thrust balance Piston 41 Inflow area 61 External conduit 62 External housing cooling hole 63 Flow space 64 Internal housing cooling hole

Claims (5)

A stator (2) having an inner housing (21) and an outer housing (22), a rotor (3), and a flow path (4) formed between the stator (2) and the rotor (3). In the flow path (4), the rotor blade rows (33) of the rotor (3) and the guide blade rows (23) of the stator (2) are alternately provided. 4), and the raw steam flows into the inflow region (41) of the flow path (4) so that the live steam flows around the rotor blade (33) and the guide blade (23) in the flow path (4). Steam turbine having a live steam conduit (5) for supply and a cooling steam conduit (6) for supplying cooling steam to a region (34) where a large thermal load of the rotor (3) acts (1)
In the steam turbine (1) having a pressure balance lateral connection (7) between the flow path (4) and the cooling steam conduit (6),
The cooling steam conduit (6) is a conduit (61) communicating with the outer housing (22), an outer housing cooling hole (62), and a flow space (63) formed between the outer housing and the inner housing. ) And at least one internal housing cooling hole (64), the pressure balance lateral connection (7) reaching the internal housing cooling hole (64) from the flow path (4), A hole in the inner housing (21);
The pressure balance lateral connection (7) is formed in the vicinity of the inflow region (41) of the flow path (4) and the region (34) where the thermal load acts in the inner housing (21). In a steam turbine
The internal housing cooling hole (64) is provided in the internal housing (21), and the internal housing cooling hole (64 ) includes the flow space (63), the rotor (3), and the internal housing. between the formed interstitial space between the (21), a steam turbine, characterized by forming the flow body technical connections.   The steam turbine according to claim 1, characterized in that the pressure balance lateral connection (7) is connected to the flow path (4) on the outside in the radial direction.   The steam turbine according to claim 1 or 2, wherein a thrust balance piston (35) of the rotor (3) is arranged in a region (34) where the heat load acts. A method for cooling a steam turbine (1), wherein raw steam passes through a flow path (4) formed between a stator (2) and a rotor (3), and the rotor (3) In the method in which the cooling steam for cooling the region (34) in which the heat load acts is supplied to the steam turbine (1),
A method characterized in that a part of the live steam is supplied to the cooling steam from the flow path (4). Live steam from the flow path (4) comprises a region of the inflow region (41) of the flow path (4), wherein the stator the rotor (3) of the internal housing (21) of (2) 5. Method according to claim 4, characterized in that it is supplied in the region (34) where the heat load acts.

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